William Z. Johnson of Audio Research: High Definition

That was a fellow engineer's response upon seeing vacuum tubes in William Z. Johnson's amplifier at a hi-fi show in 1970. Back then, the vacuum tube had been totally abandoned in favor of the transistor. In fact, the only newly made audio components based on vacuum-tube technology you could buy were guitar amplifiers. Glowing bottles were embarrassing reminders to the engineering community of just how "primitive" electronics technology had been just a short time ago.

Imagine that engineer's surprise if he could have known that, instead of setting the audio world back 20 years, Bill Johnson's pioneering return to the vacuum tube paved the way for a tube renaissance that would reach full bloom 20 years later.

To put the modern popularity of vacuum-tube audio into historical perspective, and bring you the views of the man who started the revival, I interviewed Bill Johnson at my home last December. As the founder of Audio Research and a designer of both tubed and solid-state products for the past 45 years, Bill Johnson is truly one of the founding fathers of the American high-end audio industry. I began by asking him why he wanted to build an audio amplifier in the first place.

William Z. Johnson: I've never really stopped to think through why I wanted to build my first amplifier. Back in my youth I built several amplifiers just to build them. The first one that I built commercially was in 1949. I was working for a music company in those days, after coming back from service in the Army right after World War II. I was approached by a then-audiophile who had a Klipschorn speaker and a Williamson-type amplifier. He wanted better electronics. He had caught on to the fact that the secret of good sound was not in the loudspeaker as much as in whether the electronics were transparent.

So, for some reason, he commissioned me to build him an amplifier, and I did: a three-chassis affair with a separate power supply that was electronically regulated. It was an all-triode, transformer-coupled amplifier, and evidently better than the Williamson. I say that only because he kept it—so I presume it was better. I've sort of wished over the years that I could get that back and add it to my collection of old amplifiers from the early days.

From that, I started a company of my own in 1951 called Electronic Industries. And there we did everything from building amplifiers on a one-at-a-time basis to repairing TVs and the whole gamut of electronic services in those days.

I ran that company until 1968, at which time a local company called Peploe, Inc. purchased my little company, and me, and my patent applications, and my technical files. I went to work for them as Director of Research. They acquired a number of small companies and didn't really tend to business, and things didn't work out. I obtained my freedom from that company in 1970 and started Audio Research. I guess I sort of started it by default. I really didn't know anything else—all I knew how to do was design amplifiers, so I started that with the remnants of their folly, and it's grown to what it is today.

Robert Harley: Were you the only manufacturer of tubed audio products at the time?

Johnson: No, I don't think so. I think there were probably a number of companies in Europe and the Orient that were still building vacuum-tube products, and there were certainly companies in America building musical instrument amplifiers—people like Fender and others.

I think, however, that in the high-end audio industry, I might say that I was probably the first one to bring vacuum tubes back—at least I've been given credit for that. In fact, I've been accused of it.

At a trade show in Washington, DC in 1970, I was displaying our Dual 50 and SP-1 and -2, and an engineer walked up to me. He was obviously very, very angry, and he said, "You've set the audio industry back 20 years!" [laughs] We had a discussion about it, but I don't think he was convinced.

Harley: Given the commercial domination of the transistor at the time, why did you design with tubes?

Johnson: I tried transistors, but I thought the sound that I was able to generate with various design approaches was horrendous—it was terrible. Then when FETs came along, I tried again. And while we were able to design circuits with some relatively good numbers, the sound quality still wasn't there. As the years went by, of course, that tended to change. Since then, we've made some inroads with both bipolars and FETs. Today I would have to say that our various solid-state products are probably superior to the early tube units.

In saying that, however, it's still true that, with an all-out design effort, vacuum tubes will win.

Harley: What are the technical and musical virtues of tubes?

Johnson: Technically, tubes aren't as appealing as any of the semiconductors. But musically, the devices act more like a conductor, and if I could say it humorously, than a semiconductor. [laughs] We simply find that an analog signal going through a vacuum tube doesn't seem to be harmed, whereas putting it through any kind of a semiconductor seems to hurt it.

Although I will say that, in recent years, we've been able to design good-sounding solid-state products—like the BL1 and BL2—that have only unity gain. We're using an IC chip with significant buffering both before and after it, and we've found that we can just about equal vacuum-tube sound with that, providing we stick with unity gain. The minute we try to have significant amplification with them, of course, the results are not as good.

Harley: What you said about transistors being technically appealing made me think that a 5534 op-amp looks fine on paper.

Johnson: Yeah. In fact, Bob, as an engineer and a technical person yourself, I'm sure you've become aware that the measurement techniques we use today really don't necessarily tell you about the sound quality. Obviously, if it measures badly, it isn't going to sound good. But the simple fact that it measures well doesn't assure that it will sound good.

We have to get past steady-state measurements and get into the realm of dynamic behavior—how does the circuitry perform under actual musical dynamics? So far we don't really have a good handle on how to measure and quantify that. It would be great if we could have some simple number system that would allow us to evaluate equipment sonically, but so far, that hasn't happened.